1. Field of the invention:
The present invention relates to a drain ejector in a tire vulcanizing machine for ejecting vulcanizing steam accumulated within a bladder.
2. Description of the Prior Art:
A drain ejector in a tire vulcanizing machine, which is adapted to place the inside of a bladder in communication with the outside of metal molds through a drain flow passageway and to eject the condensate of vulcanizing steam, that is, the condensate of vulcanizing steam produced during vulcanization of a tire, and which has accumulated in a lower side wall portion of a bladder, from the inside of the bladder through the drain flow passageway to the outside of the upper and lower metal molds by means of the pressure within the bladder, has been heretofore known (Japanese Utility Model Application No. 60-92217 (1985)).
A drain ejector is provided in a tire vulcanizing machine for the following reasons:
(I) Upon vulcanization of a tire, if the condensate vulcanizing steam accumulates within a bladder, a temperature difference is produced by the condensate between upper and lower portions of a tire, and it is necessary to prolong a vulcanization time in view of safety. However, if an ejector is provided in a tire vulcanizing machine, it is possible to eject the condensate of vulcanizing steam accumulated in a lower side wall portion of a bladder to the outside of the metal molds. Hence, a temperature difference is not produced between upper and lower portions of a tire and a vulcanizing time can be shortened, and at the same time the upper and lower side wall portions are uniformly vulcanized, resulting in improvement in the quality of the tires.
(II) In addition, during vulcanization of a tire, if the condensate of vulcanizing steam were not ejected from the inside of a bladder to the outside of metal molds, the condensate of vulcanizing steam would reevaporate within the bladder, and stripping resistance of the bladder would increase. In this respect, if an air ejector is provided in a tire vulcanizing machine, the condensate of vulcanizing steam accumulated in a lower side wall portion of a bladder during vulcanization of a tire can be ejected to the outside of the metal molds, and hence a stripping resistance of the bladder is reduced.
However, the above-described condensate ejector in a vulcanizing machine in the prior art presents the following problems. That is, unless a suction port of a drain outflow passageway is positioned at the deepest portion of a side wall, the condensate of vulcanizing steam cannot be ejected thoroughly from the inside of a bladder. In the above-described condensate ejector in a tire vulcanizing machine, a suction port of a drain outflow passageway is fixed in position. On the other hand, the sizes of tires to be vulcanized in a vulcanizing machine are not constant but vary. Hence, in the case where the sizes of the tires to be vulcanized change, a suction port of the drain outflow passageway cannot be positioned at the deepest portion of the side wall of the tire, and so, a problem arises in that the condensate of vulcanizing steam cannot be ejected thoroughly from the inside of a bladder.